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Conversion MB to MiB

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caps01 -  
 Jack deu -
Good evening,

Could someone clearly explain to me how to convert a value from MB to MiB?

At the moment, Google is not my friend :/. For example, if I have a file of 39 MB, how do I make the conversion?

Thanks in advance for your answers!

Configuration: Windows 7 / Firefox 9.0.1

5 answers

Answer 1 / 5
brupala Posted messages 111108 Registration date   Status Member Last intervention   14 434
 
Originally,
1 Mio contains the same amount of data as 1.048576 MB.
That's all
2 to the power of 20 on one side versus 10 to the power of 6 on the other.
And 2 to the power of 20 == 1.048576 times 10 to the power of 6.
So,
39 MB == 37.19329833984375 Mio
and ... There you go!
169
Mekthoub Posted messages 4136 Status Contributor 1 241
 
In theory, what you are saying is perfectly true. Except that in practice, it's the opposite: Totally false. Because in practice, the vast majority, if not almost all software, operating systems, and others that display sizes labeled in MB... actually calculate in computer megabytes, that is to say in powers of 2. They use MB as a synonym for MiB. So in most real cases, 39 MB == 39 MiB.

Almost all, but there are still exceptions. The most well-known is the advertising from hard drive manufacturers. The 500 GB drive really is 500 GB, strictly speaking. So only 465 GiB. And once installed under Windows, it appears with a total capacity of 465 "GB", or a little less.

In my opinion, 465 is the right number. That's the one we, computer users, need to know. That's the one that will serve us to store files of that size. However, the label "GB" is ambiguous: 2^30 or 10^9? Metric system, or computing? We could resolve this ambiguity by increasingly using explicit labels: MiB, GiB, and the whole bunch. But in practice, and except for exceptions, MB is a synonym for MiB.
2
brupala Posted messages 111108 Registration date   Status Member Last intervention   14 434
 
Mekthoub,
it's your logic but it's not reality.
It's you (and those who think the same way) who read Mio where it says Mo: when it says Mo (or MB), today we must read Mo, that's all.
Besides, everyone works with rounded values, there's no point in complicating things by nitpicking on details when it's not necessary.
But here the question was precise and the answer must be, otherwise the question wouldn't have been asked if the author hadn't had doubt.
In any case, on the bit balance, 1 Mio>1 Mo and no dialectics can change that.
4